A stochastic formulation for the drag force based on multiscale numerical simulation of fluidized beds

•Micro-scale particle resolved and meso-scale DEM-CFD simulations of a small size fluidized bed,•Characterization of the drag coefficient as a probability density function for a pair of (Reynolds, porosity),•New stochastic drag model with parameters extracted from micro-scale particle-resolved simulations,•Improvement of classical DEM-CFD models using a Gaussian filtering kernel and a new stochastic drag model to recover the right level of particles fluctuations.